(a) Field of the Invention
The present invention relates to a liner mounting structure for measuring piston friction, and more particularly, to a liner mounting structure for measuring piston friction in which the influence of combustion pressure acting on a liner is removed, and floating of the liner is made easy.
(b) Description of the Related Art
In an internal combustion engine, the energy created by the combustion of fuel in a combustion chamber, less the energy lost due to dissipative forces, is used in propelling a vehicle. Since piston friction is one of the major sources of energy dissipation, it is necessary to reduce the energy lost in this manner so that engine power may be increased and fuel consumption reduced.
That is, friction generated between the piston and cylinder liner is not only one of the major sources of dissipation, it is a source of dissipation that can be reduced by better design, whereas many of the other sources may only be reduced minimally if at all and only with limited gains in performance. Therefore, much research has gone into reducing piston friction, as well as into ways to more precisely measure the friction generated between the piston and cylinder liner.
In order to directly measure the friction between the piston and cylinder liner, a strain gauge or load cell is used to measure the force generated by the vertical displacement of the cylinder liner occurring as a result of friction with the piston.
FIG. 1 shows an example of a conventional apparatus and related elements used to measure friction between a piston and a cylinder liner.
As shown in the drawing, a cylinder liner 120 is provided within a cylinder block 110, and a piston 130 is provided within an area defined by the cylinder liner 120. The cylinder liner 120 receives upward and downward force by friction generated by the rectilinear motion in the vertical direction of the piston 130. The cylinder liner 120 is designed to undergo minute movement in the vertical direction by the received force. As a result, the cylinder liner 120 is also referred to as a floating liner.
A device for measuring pressure generated by the vertical movement of the cylinder liner 120 is provided contacting the cylinder liner 120. An example of such a conventional device is shown in FIG. 1. In particular, provided to one side and at a lower-portion of the cylinder liner 120 is a load cell body 170 and a load cell 175.
A small space may result between a cylinder head 140 and an upper end of the cylinder liner 120. When fuel undergoes combustion in the combustion chamber, the explosive force acts in this space to displace the cylinder liner 120 in a downward direction (the explosive force is typically many hundred times greater than the force of friction between the cylinder liner 120 and the piston 130), thereby resulting in experimental error, that is inaccurate measurements of friction. Accordingly, a sealing folder 150 is interposed in the space between the cylinder head 140 and the upper end of the cylinder liner 120. The upper end of the cylinder liner 120 moves vertically within the sealing folder 150 such that the explosive force of combustion is prevented from acting on the cylinder liner 120.
However, in order to install the sealing folder 150 between the upper end of the cylinder liner 120 and the cylinder head 140, the piston 130 must be fabricated such that no contact occurs between the piston 130 and the sealing folder 150. That is, an outer edge of the piston 130 must be clearanced by as much as the sealing folder 150 protrudes into the combustion chamber. As a result, a moment of inertia of the piston 130 is altered such that the rectilinear motion of the piston 130 is also changed. This, in turn, modifies the contact resistance (i.e., friction) between the cylinder liner 120 and the piston 130 such that the precise measurement of friction between these elements cannot be performed.
Further, a lateral direction stopper 160 is used in the prior art to enable more precise measurements of friction between the cylinder liner 120 and the piston 130. The lateral direction stopper 160 acts to limit the side-to-side movement of the cylinder liner 120 by providing an opposing, lateral force thereto so that the friction generated is that of only the vertical motion of the piston 130. However, friction is generated between the lateral direction stopper 160 itself and the cylinder liner 120 by this opposing force in the lateral direction such that errors occur in the measurement of the friction between the piston 130 and the cylinder liner 120.
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide a liner mounting structure for measuring piston friction in which pressure forces acting on a liner are offset, and floating of the liner in a vertical direction is made easier.
To achieve the above object, the present invention provides a liner mounting structure for measuring piston friction in which a liner is mounted in a a cylinder block of an internal combustion engine and is cylindrically shaped to define a space in which a piston undergoes rectilinear motion, the liner mounting structure comprising a protrusion formed around an outer circumference of the liner at an upper portion of the liner; a combustion pressure passageway formed in the liner starting from an upper surface of the liner and extending downwardly to a bottom surface of the protrusion; an indentation formed in the cylinder block corresponding to a position of the protrusion of the liner; an upper O-ring groove formed in the cylinder block above the indentation, a lower O-ring groove formed in the cylinder block below the indentation, a center O-ring groove formed in the cylinder block within the indentation; and an upper O-ring mounted in the upper O-ring groove, a lower O-ring mounted in the lower O-ring groove, and a center O-ring mounted in the center O-ring groove.
According to a feature of the present invention, a plurality of the combustion pressure passageways are formed equidistantly starting from the upper surface of the liner.
According to another feature of the present invention, an area of a bottom surface of the protrusion is equal to an area of the upper surface of the liner.
According to yet another feature of the present invention, an area of an upper surface of the protrusion on which atmospheric pressure acts is equal to an area of a bottom surface of the liner.
According to still yet another feature of the present invention, a diameter of the center O-ring is equal to a sum of diameters of the upper and lower O-rings.
According to still yet another feature of the present invention, the liner mounting structure further comprises an atmospheric pressure passageway formed in the cylinder block between the upper O-ring groove and the center O-ring groove such that atmospheric pressure is provided in a space defined by the liner, the upper O-ring groove, the center O-ring groove and the cylinder block.
According to still yet another feature of the present invention, the liner mounting structure further comprises a lateral supporter mounted in the cylinder block, the lateral supporter preventing displacement of the liner in a lateral direction.
According to still yet another feature of the present invention, a plurality of lateral supporters is provided in the cylinder block.
According to still yet another feature of the present invention, the lateral supporter comprises a liner support member, an innermost face that is in close contact with the liner, and an outermost face that includes a plurality of support grooves, the liner support member being fixedly mounted encompassing an outer circumference of the liner; a cylinder block support member provided at a predetermined distance from the liner support member in a direction away from the liner, an outermost face of the cylinder block support member being in close contact with the cylinder block, and a plurality of support grooves being formed in an innermost face of the cylinder block support member; and a plurality of support plates inserted in a pair of corresponding support grooves of the liner support member and the cylinder block support member, the support plates being formed at a predetermined thickness.
According to still yet another feature of the present invention, the support plates are formed at identical thicknesses.